Create a new “Aggregate Device” using the pull down menu at the left bottom corner.

Check “Use” for the Built-in Microphone and Built-in Output records

Press Command+Space, look for “Quicktime” Application and Open quicktime.

On Quicktime select, File -> New Screen Recording or New Audio Recording, depending on if you want to record the skype call and the screen of your partner or just the conversation audio.

Using the white arrow at the left of quicktime, select the newly created Aggregated Device. At this point you should note that if you say something the indicator on quicktime is gonna indicate that your voice is being listened. Also if you play a sound, (for example a track using iTunes or a Youtube video) you will also note that the indicator moves.

Once you have started your skype Call, press the red “Record” button. This way quicktime is gonna record the output audio, the input audio and the screen optionally.

No additional programs are required (Audacity, Soundflower, LineIn) etc. You must have Mac OS 10.8+